Certainly boiling after the Millbank bag is my method of choice, but I wanted a bombproof method for use on occasions where that is not possible for some reason.
Most water filters require time and effort to use, replacement filters and do not deal with viruses unless they have an iodine element.
The Millbang bag gets rid of large particles by just hanging it up. Boiling or chemical traetment can be done while something else is happening.
Life's too short for carrying and pumping filters as far as I can see.
I've certainly thought of making my own iodine crystal bottle but what I like about the Polar Pure idea is that it is small, self contained, has the dose instructions permanently marked on the bottle (who can remember amounts and times after two or three years of not needing them), seems to deal with most water hazards including viruses ( excluding cryptosporidium of course) with no shelf life problems.
I don't mind paying a little extra for a good piece of kit providing it does exactly what it says on the bottle
It would be nice though to be able to get it from the UK if possible.